This invention relates to mechanical-to-electrical transducers and more particularly relates to a contactless magnet-activated electrical-power "proportional" controller.
A variety of mechanical to electrical "proportional" controllers are known. As used herein, the term "proportional" means continuous but not necessarily linear.
Lamp dimmers that operate from an AC voltage source have become a well known commodity. They employ three-leaded controlled rectifiers in combination with manually operable potentiometers. Motor speed controllers also use controlled rectifiers, or amplifiers, in association with manually operable potentiometers. It is also known to make controllers for being powered by a DC voltage source usually including a DC powered amplifier.
Magnet activated circuits such as the ferrous article proximity sensors are described in U.S. Pat. Nos. 4,296,410 to Higgs; 4,443,716 to Avery and 5,045,920 to Vig et al, all of which are assigned to the same assignee as is the present invention. Each of these circuits includes a Hall element and Schmitt trigger circuit having an input that is connected to the output of the Schmitt trigger circuit so when the ambient magnet field exceeds a value at which the corresponding voltage exceeds the threshold voltage of the Schmitt trigger circuit, the output of the Schmitt trigger circuit changes from one binary state to the other. These circuits are switching controllers and not proportional controllers.
It is an object of the present invention to provide a proportional controller for generating an average output voltage that is proportional to the strength of an ambient magnetic field.
It is a further object of this invention to provide such a controller including a magnet that is movably mounted adjacent the controller circuit for altering the ambient magnetic field.
It is yet a further object of this invention to provide such a controller circuit in the form of an integrated circuit which is particularly well suited for operation from a source of low DC voltage.